Telematics services are services that are provided by a call center to a vehicle and/or to the operator of a vehicle that relate to various needs of the vehicle or the operator. Telematics services commonly include, but are not limited to, the remote monitoring of vehicle maintenance needs, the provision of turn by turn navigation guidance, the provision of theft tracking services after a vehicle has been stolen, the provision of door unlock services when the vehicle's owner is locked out of the vehicle, and the coordination of emergency services after a vehicle collision or other emergency, to name just a few.
A telematics service system conventionally includes a telematics unit associated with the vehicle, a call center that is located remotely from the vehicle, and a communication network that communicatively connects the two. In a known example, the telematics unit is embedded in the vehicle (i.e., mounted to the vehicle during vehicle assembly) and directly connected to the vehicle bus. This connection to the vehicle bus permits the telematics unit to provide many of the telematics services. For example, an embedded telematics unit may be configured to determine when the vehicle has been involved in a collision by monitoring message traffic across the vehicle bus and detecting a message transmitted by the vehicle's air bag modules indicating that there has been an airbag deployment.
Aftermarket telematics units are also available in the market place. The term “aftermarket”, when used in conjunction with the term “telematics unit” shall refer to a telematics unit that is not embedded in the vehicle (i.e., not mounted to the vehicle during vehicle assembly) but rather which is provided as a separate component from the vehicle by either an original equipment manufacturer or by another supplier after the vehicle has been assembled. Such aftermarket telematics units make it possible for drivers of vehicles that lack an embedded telematics unit to, nevertheless, receive some or all of the available telematics services. One service that such aftermarket telematics units are configured to provide is assistance to a driver and/or other occupants of the vehicle after a collision has occurred. However, because the aftermarket telematics unit is not an embedded telematics unit, it may not be communicatively coupled with the vehicle bus and may therefore be unable to receive message traffic sent by the vehicle's air bag module.
Accordingly, example aftermarket telematics units are equipped with independent collision detection units (e.g., gyroscopes; accelerometers, etc . . . ) that enable an aftermarket telematics unit to detect a collision. Some collision detection units may operate by detecting and/or measuring accelerations along various axes of the vehicle. When a significant acceleration is detected, the collision detection unit may be configured to conclude that a collision has occurred.